Halftone plate and process of producing same



Feb. 10. 1925.

1,525,531 E. BASSIST HALFTONE PLATE AND PROCESS OF PRODUCING SAEEOriginal Filed Feb. 17, N22

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ELLIS BASSIST, OF WESTWOOD, NEW JERSEY, ASSIGNOR TO GEORGE H. KINGSLEY,

OF NEW YORK, N. Y.

HALFTONE PLATE AND PROCESS OF PRODUCING SAME.

Application filed February 17, 1922, Serial No. 537,255.

To all whom it may concern:

Be it known that I, ELLIS BASSIST, a citizen of Hungary, wood, in thecounty of Bergen and State of Xew Jersey, have invented certain new anduseful Improvements in Halftone Plates and Processes of Producing Same,of which the following is a specification.

The invention relates to the art of ing a negative (positive) plate foruse in making lithographic printing plates, and to the novel negative.or positive produced thereby. It has for its object to simplify theprocedure now in common use and to greatly reduce the number of stepsnow required in the preparation of a negative of this character.

A further object of the invention consists in a novel form of halftonenegative or positive plate, which is finished as to tone and colorvalues and is suitable for making directly therefrom the zinc oraluminum printing plate used in lithographic printing.

The nature of the invention, however, will best be understood whendescribed in connection with the accompanying drawings which arediagrammatic views illustrating the invention, and in which Fig. 1represents a transparent base upon which a photographic reproduction isto be provided.

Fig. 2 represents the said base with a covering of opaque materialprovided thereon.

Fig. 3 represents a similar view, but in which said covering has beencoated with a sensitized emulsion.

Fig. 4 represents the reproduction after exposure and fixing.

Fig. 5 is a similar view after the preliminary etching operation.

Fig. 6 represents the negative in its final form, ready for use inmaking a lithographic printing plate therefrom.

Similar characters of reference designate corresponding parts thruoutthe several views.

Referring to the drawings, 10 designates a suitable transparent base,preferably of glass; but whichmay consist of a film of any suitablematerial as gelatine or celluloid, or paper or other material in thenature of a plate and transparent. This plate is provided on one surfacewith a thin opaque covering 11 as of copper, zinc or other suitand aresident of West? prepar material is employed, a

Renewed June 27, 1924.

able material which may be deposited thereon, for example byelectrochemical means, 0.1, as a sheet thereof glued thereto. Over saincis provided a thin coating 12, (Fig. 3) of a sensitized emulsion such asthe bichromate glue solution commonly employed by photoengravers. Tothis end, the surface 11 is carefully cleaned and a sensitized emulsion,for example composed of fish glue, chromic acid, water and ammoniumbichromate. flowed uniformly thereovcr and allowed to dry thereon.

In accordance with the invention, the plate thus prepared is exposed tolight, face to face with a suitable halftone positive (negative), thenbathed in cold water and washed with spray of water. This results in thedissolution and removal of the unexposed portions of those areas of thesensitized emulsion on the plate which were under the dark areas of thepositive during exposure. The remaining portions 13.. (Fig. 4) are fixedthereby, and are allowed to dry and harden. The fixed portions 13 arethen subjected to heat to indurate the field. as by burning in with gasflame to carbonize the fixed glue solution and make it thoroughlyresistant to the etching solution subsequently applied. \Vhen a base ofinflammable cold treatment may be applied for this purpose.

The plate, is then etched, as by bathing in any wellknown etchingsolution. which will cut thru to the transparent base 10 and outline thedesign on the transparent bed or support. The plate may then besubjected to further operations, including etching and re-etching tocorrect the same, by staging, as to tone and color values, as is wellunderstood in the art. The operations may be repeated, if required, asuitable acid resisting substance. such as asphaltum varnish beingapplied to the finished portions.

In this manner. a finished negative of a positive. Fig. f, orthe reverseas the case may be. is secured and which is suitable for directreproduction upon a zinc or aluminum plate andout of which the finallithographic printing plates are made in manner well understood.Thereby. a number of steps of an intricate and highly technical nature,as well as a number of plates, are eliminated and a very satisfactoryre-etched or color corrected halftone negative obtained.

. I claim 1. The process of preparing a plate for use in makinglithographic printing plates, which consists in covering a base oftransparent material with an opaque substance,

sensitizing the surface of said covering, ex-

posing the sensitized surface "to light thru the object to be reproducedand fixing the exposed portion, removing the portions of'the opaquecoating under the unexposed portion and correcting for the desired toneand color values.

2. The process of preparing a plate for use in making lithographicprinting plates, which consists in coating 2. base of glass with anopaque substance, sensitizing the surface of said covering, exposingsaid surface to light thru the object to be reproduced and fixing theexposed portion, etching away the opaque covering at the line); posedportion, and correcting the plate for tone and color values.

3. The process of preparing a plate for use in making lithographicprinting plates, which consists in covcring a base of transparentmaterial with metal, sensitizing the surface of said metal, exposingsaid sensiin making lithographic printing plates,

which consists in covering a base of glass with metal, sensitizing thesurface of the metal, exposing said-sensitized surface to light thru theobject to be reproduced and I fixing the exposed portion, induratingsame,

etching away the metal at the unexposed portion, and correcting theplate for tone and color values. I

5. A finished halftone plate for use in making directly therefromlithographic printing plates, comprising a transparent base, and anetched, opaque, metallic covering with exposed and tone and color valuecorrected photographic surface, portions of the metallic covering beingabsent to outline the desi n to' be reproduced.

Signe at New York, in the county of New York and State of New York, this10th day of February, A. D. 1922.

ELLIS BASSIST.

